Demand inhalator



June 27, 1961 EARLY 2,989,970

DEMAND INHALATOR Filed Sept. 5, 1956 e8 42 4 4. 77 {H J72 68 b 82 :2

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United States Patent 2,989,970 D INHALATOR Paul F. Early, Dayton, Ohio, assignor to Globe Industries, Inc., a corporation of Ohio Filed Sept. 5, 1956, Ser. No. 608,040 '12 Claims. (Cl. 137-63) This invention relates to inhalators for supplying special gases and medicaments to a patient and more particularly to an inhalator responsive to the demands of the patient. 7

The demand inhalator of this invention is the type wherein a patient wearing a face mask attached to the inhalator inhales and exhales through the inhalator. As the patient inhales, a gas is introduced into the inhalator for inhalation by the patient. The amount of gas introduced is in proportion to the demand of the patient. When the patient eXhales, the flow of gas into the inhalator is interrupted and the exhaled gases are vented to the ambient atmosphere.

One object of the present invention is to provide an inhalator fully responsive to the demands of the user. To achieve this characteristic, the flow of gas into the inhalator is regulated by a pressure sensitive diaphragm biased with a substantially constant force such that the force required to actuate the inhalator is independent of the gas volume delivered by the inhalator.

Another object of this invention is to provide in an inhalator a novel lever arrangement for actuating a stop valve in response to movement of a pressure sensitive diaphragm. The lever arrangement has the characteristic of providing high mechanical advantage in a limited space. Y

A further object of this invention is to provide in an inhalator a pressure sensitive diaphragm functioning as a flapper valve providing for exhalation by the patient.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of op eration, as will become more apparent from the following description.

In the drawings, FIGURE 1 is a perspective view of the inhalator with an end portion removed to expose the inner mechanism.

FIGURE 2 is a top plan view of the inhalator of FIGURE 1.

FIGURE 3 is a sectional view taken substantially along -the line 33 of FIGURE 2.

FIGURE 4 is a sectional view taken substantially along the line 44 of FIGURE 3, the view showing in section the end portion removed in FIGURES l, 2,

and 3.

FIGURE 5 is an exploded detail perspective view of support members employed in the inhalator.

Referring to the drawings in detail, the inhalator is housed in a substantially cylindrical housing including a tubular member 12 and end plates 14 and 16. The inner wall of the tubular member 12 is provided with diametrically opposite facets 13 and 15 for purposes to be described in detail in the following. At one end of the tubular member 12 is an annular outwardly extending flange 18 having an annular recess 20 therein. A flexible membrane or diaphragm 22 having an annular rib 24 at the margin thereof seated in the annular recess 20 extends radially across the tubular member 12.

The end plate 14 closes the end of the tubular member 12 adjacent the diaphragm 22 and is secured to the annular flange 18 by any suitable means. The margin of the diaphragm 22 provides a gasket for sealing the gap between the end plate 14 and the flange 18.

The end plate 16 shown in FIGURE 4, is secured to the opposite end of the housing 10 by any suitable means. A conduit 26 integral with the end plate 16 is 2,989,970 Patented June 27, 1961 and the diaphragm 22 thus define a chamber 28 withinthe housing 10 which communicates throughvthe conduit 26 to a face mask or the like and ultimately with the lungs of a person using the inhalator. l i

To provide for exhalation through the inhalator'housing, the central portion of the diaphragm 22 is utilized as a flapper valve. A rigid disc or plate 30, seen best in FIGURE 2, is secured to the inner surface of the diaphragm 22, the disc being provided with an annular ring of apertures or perforations 32 adjacent the perimeter thereof. Opposite the unperforated central portion of the disc 30, the diaphragm 22 is provided with an aperture 34, the aperture being smaller than the unper'forated portion of the disc. An aperture 36 is also located centrally in the end plate 14. Clearly, if the pressure within the chamber 28 rises above atmospheric pressure, air or gas will move through the perforations 32 in the disc 30, forcing the apertured central portionof the. diaphragm outwardly, the gas escaping to the ambient atmosphere. When the pressure in the chamber 28 falls below that of the ambient atmosphere, the diaphragm 22 will be drawn tightly against the disc 30, closing the perforations therein and prohibiting the passage of air from the ambient atmosphere into the chamber 28.

The diaphragm is protected by a perforated shield 38, the shield 38 and disc 30 being secured together by rivets '40 passing through the diaphragm 22. The shield 38 is arched outwardly from the diaphragm 22 to allow the central portion thereof to perform as a flapper valve.

A gas for inhalation by the person using the inhalator is supplied to the chamber 28 through a conduit 42 in the wall of the tubular member 1 2. The gas may be supplied under pressure from any suitable reservoir. The flow of gas into the chamber 28 is regulated by a stop valve 44, preferably constructed from a resilient material, adapted to seat in the conduit 42. The stop valve 44 is mounted upon one end of a shaft 46 traversing the chamber 28. The other end of the shaft 46 is journalled for sliding motion into a T-shaped support block 48 mounted upon the facet 15 on the opposite side of the tubular member 12. A spider member 50, secured to the shaft 46 adjacent the stop valve 44 and engaging the wall of the conduit 42, centers the valve with respect to the conduit 42, without restricting the passage of gas through the conduit 42 and around the stop valve 44.

The flow of gas through the conduit 42 into the chamber 28 is regulated in accordance with the pressure in the chamber 28 by a lever arrangement which will now be described.

Struck out from the disc 30 are two opposing lugs 52 and 54 each provided with an aperture therein. A bracket member 56 provided with apertured lugs 58 at one end thereof is pivotally secured to the lugs 52 by a suitable pin 60 passing through the apertures in the lugs 52 and 54. A U-shaped cut out portion in the opposite end of the bracket member 56 defines two legs 62 and 62a in the bracket member, each leg being provided with a pair of parallel apertured lugs 64 and 64a. The legs of the bracket member 56 extend substantially perpendicular to the plane of diaphragm 22 into the chamber 28.

Two levers, 66 and 68, are pivotally secured to the leg 62 by a pin 70 passing through the apertures in the lugs 64. Similarly, two levers, 66a and 68a, are pivotally secured to the leg 620 by a pin 70a passing through the apertures in the lugs 64a. The levers 66 and 66a, which are longer than the levers 68 and 68a, are pivotally secured at their opposite ends to the legs of a U-shaped block 72 mounted adjacent the T-shaped block 48 on the t facet 15 of the tubular member 12. Pins 74 and 74a,

there being one journalled in each leg of the U-shaped block 72, provide the pivotal axes for the levers '66 and 66a, respectively.

I The levers .68 and 6811 are pivotally secured at their opposite ends to a block 76 mounted upon the shaft 46 which supports the stop valve 44. Pins 78 and 78a, journalled in the block 76 in substantial radial alignment with the shaft 46, provide the pivotal axis for the levers 68 and 68a, respectively. The block 76 is fixedly secured t the shaft 46 by a set screw 77, as shown in FIGURES 2 an 7 To prevent rotation of the shaft 46 and the block 76 secured thereto, the levers 68 and 68a secured to opposite sides of the block 76 are made substantially triangular in shape, as shown in FIGURES 1 and 3, thereby creating a large bearing surface for the block 76. A bracket member, 79, sandwiched between the T-shape block 48 and the facet 15 of the tubular member 12, is provided with parallel projecting flanges 80 extending on either sideof the levers 68 and 68a, which flanges function to fix the angular orientation of the block 76 and therefore the shaft '46.. The arrangement of the bracket member 79, T-shaped block 48, and U-shaped block 72 is shown in exploded detail in FIGURE 5.

As best seen in FIGURE 3, the levers 66 and 66a extendsubstantially normal to the bracket member 56 and parallel to the plane of the diaphragm 22. The leversf68 and 68a, which can be represented by imaginary lines extending from the pivot pins 70 and 70a to the pivot pins 78 and 78a, extend at an obtuse angle relative to the bracket member 56. It is apparent that as the pressure in the chamber 28 falls belowatmospheric pressure, the diaphragm 22 will move axially into the chamber 28 forcing the bracket member 56 to move axially upwards, as viewed in FIGURE 3. 'The maximum upward movement of the bracket member 56 is determined by the U-shaped cut out portion therein which provides clearance for the shaft 46. As the bracket member 56 moves axially upwards, the effective angle between the lever pairs 66 and 68, and 66a and 6811, will decrease approaching zero angle. The block 76 is thereby constrained to move axially, carrying with it the shaft 46 and displacing the stop valve 44, so as to open the conduit 42. Due to a mechanical advantage in the lever arrangement, the force moving the stop valve 44 is many times greater than the force exerted by the diaphragm '22. e

The lever structure just described is referred to hereinafter as substantially constituting a double slider-crank mechanism: one slider-crank mechanism consisting of levers 66, 68 and the slider block 76; and the other slidercrank mechanism consisting of lever 66, lever 56 and-the slider "block or lug 52.

It can be shown mathematically that, to'a'firstapproxi mation, the mechanical advantage of the lever arrangement is proportional to the cotangent of the angle between the levers 66 and 68. Thus, as this angle approaches zero, the mechanical advantage becomes infinite. By adjusting the size and proportion of parts, the angle between the levers 66 and 68 can be adjusted over a wide range, thus varying the mechanical advantage as desired. It is, of course, apparent that as the-mechanical advantage increases, the displacement of the stop valve 44 decreases, placing a'practical limitation upon the mechanical advantage.

Due to the pressure of the gas in the conduit 42, as

well as gravitational effects, it is not only desirable, but necessary,to bias or load the diaphragm 22 to its extreme position in the housing 10. This is accomplished by providing a pair of hairpin springs 82 an'd'82a attached to fixed s'upports'84 and 84a. The supports 84 and 84a are'mounted in fixed spaced relation to the facet 13 by threaded shafts 86 and 86a, respectively, the supports 84, and 84a being securedto the threadedshafts 86 and 86kt bysuitable-nuts-88. Rods 90. and 90a projecting normally from the facet 13 through suitable apertures in the supports 84 and 8411, respectively, orient the supports axially in the chamber 28.

In each support 84 and 84a, a plurality of axially aligned apertures 92 are provided. One arm of the hairpin spring 82 is projected into a suitable aperture in the pin 70 in the bracket member 56, and the other arm of the hairpin spring 82 is projected into one of the apertures 92 of the support 84, to thereby secure the spring 82 to the support. Similarly, the arms of the spring 82a are secured respectively to the pin 7 0a in the bracket member 56 and the support member 84a.

It is to be noted that the full spring tension of each spring is directed upon the pins 70 and 70a and only the axial component of this tension is transmitted to the diaphragm 22. As viewed in FIGURE 3, an imaginary line passing through the ends of the spring 82 will make an acute angle with the lever 66. The axial component of the spring tension delivered by the spring 82 will be determined approximately by the product of the spring tension times the sine of this acute angle for relatively small displacements of the diaphragm 22.

Clearly, as this angle approaches zero, the axial component of the spring tension approaches zero. By varying the axial position of the arm of the spring 82a secured to the support 84a, the axial component of the spring tension can be varied over a wide range, to thereby adjust the loading of the diaphragm 22. The same reasoning applies to the spring 82a.

As the bracket member 56 moves axially in the chamber 28, being driven by the diaphragm 22 in response to pressure reduction in the chamber 28, the axial component of the spring tension decreases. Simultaneously, the springs 82 and 82a must be compressed slightly as the'bracket member 56 moves axially, thereby increasing the total tension delivered by each spring. By proper arrangement of parts, the variation in spring tension opposing the axial movement of the diaphragm 22 is adjusted to just compensate the increasing restoring force of the diaphragm itself so as to produce a substantially constant force biasing the diaphragm into the home position, the net restoring force on the diaphragm being thereby independent of the displacement of the diaphragm.

It is important to note that the springs 82 and 82a must be so positioned that the ends thereof must never become aligned with the lever 66. Otherwise, it would be possible to obtain a finite diaphragm displacement which is stable, or biased oppositely, so that the diaphragm 22 would not return to its home position when the pressure in the chamber 28 is equal to that of the atmosphere. In the operation of the inhalator, a face mask is attached to the conduit 26 and a source of gas under pressure is connected to the conduit 42. As the patient inhales through the conduit 26, the pressure in the chamber 28 lowers below that of the ambient atmosphere. As soon as the'pressure differential across the diaphragm 22 is sufiicient to overcome the loading of the diaphragm 22, the diaphragm moves axially, opening the stop valve 44.

As the stop valve 44 opens, gas passes through the conduit 42 into the inhalator chamber 28 and eventually to the patient. The diaphragm will quickly move to a position such that the amount of gas flowing into the chamber 28 equals the amount demanded by the patient, the patient maintaining a negative lung pressure just sufficient to overcome the opposing force of the diaphragm 22 and springs 82 and'82a. Since this force is substantially constant and independent of the diaphragm displacement, the negative pressure the patient mus-t maintain is independent of the volume of gas demanded by the patient. The patient thus obtains a proper amount of gas without experiencing a resistance or drag in the inhalator as he attempts-to increase or decrease his breathing volume.

As the patient ceases to inhale, the pressure in the chamber 28 approaches atmospheric pressure and the diaphragm 22 actuates the stop valve 44 to close the gas inlet. The force with which the gas inlet is closed is determined by the loading of the diaphragm 22, amplified by the mechanical advantage of the lever mechanism.

When the patient exhales, the diaphragm Q2 cooperating with the disc 30 operates as a flapper valve to release the exhaled gas to the ambient atmosphere.

In the event of failure of the inhalator mechanism, as, for example, the stop valve 44 becoming jammed in the open position, the flapper valve operation of the diaphragm 22 provides a safety feature for the patient. The instant the pressure in the chamber 28 rises above atmospheric pressure, gas is vented through the aperture 34 in the diaphragm 22 out of the chamber 28. Thus, it is impossible to create a pressure in the chamber 28 substantially greater than atmospheric pressure.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In a demand inhalator for attachment to a face mask or the like of the type including: a housing defining a gas receiving chamber; means providing a gas inlet to said chamber; valve means for regulating the flow of a gas through the gas inlet; and an inherently resilient pressure sensitive means responsive-to the gas pressure within said chamber, wherein the said pressure sensitive means undergoes a displacement in response to pressure changes within said chamber; the combination therewith of a valve operating linkage means responsive to displacement of said pressure sensitive means and mechanically interconnecting the latter to said valve means for actuating said valve means in proportion to the displacement of said pressure sensitive means; and yielding means interposed in said linkage means with one end of said yielding means being afiixed to a movable pin connection of said linkage means for pivotal and translational movement with said pin, whereby said yielding means may be made to supplement the inherent resiliency of said pressure sensitive means so as to bias pressure sensitive means with a substantially constant force independent of the displacement thereof.

2. A demand inhalator according to claim 1 wherein the other end of said yielding means is affixed to an adjustable fixed pivot whereby the magnitude and the direction of the biasing force exerted upon said diaphragm may be selected as desired.

3. In a demand inhalator for attachment to a face mask or the like of the type including: a housing defining a gas receiving chamber; means providing a gas inlet to said chamber; resilient pressure sensitive means responsive to a gas pressure differential between said chamber pressure and atmospheric pressure, said pressure sensitive means undergoing a displacement when the gas pressure within said chamber is below that of the ambient atmosphere; and valve means associated with said gas inlet; the combination therewith of a valve operating linkage means comprising a pair of slider crank mechanisms, the turning pair of one of said mechanisms being pinned to the tuming pair of the other of said mechanisms, biasing means interconnected at said common pinned interconnection between the turning pairs of said mechanisms, said linkage means being responsive to displacement of said pressure sensitive means and mechanically interconnecting the latter to said valve means for displacing said valve in proportion to the displacement of said pressure sensitive means with varying mechanical advantage as said linkage means travels.

4. The demand inhalator according to claim 3, wherein one link of the turning pair of one of said mechanisms is common to a link of the turning pair of the other of said mechanisms.

5. A demand inhalator according to claim 3 wherein said valve means constitutes the slider of one of said mechanisms and the displacement of said pressure sensitive means approximates rectilinear motion.

6. In an assembly including a housing providing a gas receiving chamber, pressure sensitive means responsive to pressure variations in said chamber, means providing a gas inlet to said chamber, means providing a ga outlet from said chamber, valve means disposed in said gas inlet, said valve means having an open position and a closed position: valve operating means responsive to said pressure sensitive means for positioning said valve means, and yielding means biasing said pressure sensitive means, said valve operating means including a shaft engaging said valve means and so mounted as tobe constrained to translational motion, a first lever, means pivotally securing one end of said first lever to said shaft, a second lever, means pivotally securing one end of said second lever to the other end of said first lever, said yielding means being connected to the pivotal connection between the first and second levers, means pivotally securing the other end of said second lever to said housing, said first and second levers being disposed at an acute angle with respect to one another, and further linkage means pinned to and operated by said pressure sensitive means pivotally engaging at least one of said levers.

7. A demand inhalator for attachment to a face mask or the like including, in combination: a housing defining a gas receiving chamber; means providing a gas inlet to said chamber; valve means for regulating the flow of a gas through the gas inlet; an inherently resilient pressure sensitive means responsive to the gas pressure Within said chamber, said pressure sensitive means undergoing a displacement in response to pressure changes within said chamber; valve operating linkage means approximating a double slider-crank mechanism responsive to displacement of said pressure sensitive means and mechanically interconnecting the latter to said valve means for displacing said valve in proportion to the displacement of said pressure sensitive means with varying mechanical advantage as said linkage means travels, and yielding means interposed in said linkage means with one end of said yielding means being afiixed to a movable pin connection of said linkage means and the other end of said yielding means being affixed to an adjustable fixed pivot so arranged that the magnitude and the direction of the biasing force exerted upon said diaphragm may be selected as desired, and the yielding means supplements the inherent resiliency of said pressure sensitive means so as to bias said pressure sensitive means with a substantially contant force independent of the displacement thereof.

8. The demand inhalator according to claim 7, wherein said linkage means comprises a pair of slider crank mechanisms, the turning pair of one of said mechanisms being pinned to the turning pair of the other of said mechanisms.

9. The demand inhalator according to claim 8, wherein one link of the turning pair of one of said mechanisms is common to a link of the turning pair of the other of said mechanisms.

10. A demand inhalator according to claim 7 wherein said valve means constitutes the slider of one of said mechanisms and the displacement of said pressure sensitive means approximates rectilinear motion.

11. The demand inhalator of claim 7 wherein said valve operating means includes a shaft engaging said valve means and so mounted as to be constrained to translational motion, a first lever, means pivotally securing one end of said first lever to said shaft, a second lever, means pivotally securing one end of said second lever to the other end of said first lever, means pivotally securing the other end of said second lever to said housing, said first and second levers being disposed at an acute angle with respect to one another, and a third lever, means pivotally securing one end of said third lever to the pivotal connection between said first and second levers, and means pivotally securing the other end of said third lever to said pressure sensitive means.

12. In a demand inhalator for attachment to a face mask or the like of the type including a housing defining a gas receiving chamber; means providing a gas inlet to said chamber; valve means for regulating the flow of a gas through the gas inlet; and an inherently resilient pressure sensitive means responsive to the gas pressure Within said chamber to move alternately to two opposed extreme positions from a neutral unactivated position, wherein the said pressure sensitive means undergoes a displacement in response to pressure changes within said chamber; the combination therewith of a valve operating linkage means responsive to displacement of said pressure sensitive means and mechanically interconnecting the latter to said valve means for actuating said valve means in proportion to the displacement of said pressure sensitive means; said valve operating linkage means including a bracket member pivotally secured at its one end to said pressure sensitive means, said bracket member at its end furthest from said pressure sensitive means being formed in a bifurcated portion, there being a pair of valve operating linkage means pivotally attached, separately, at one end, one to each of the furcations of said bracket, and pivotally attached at their other ends to a portion of said valve means, yielding means for loading said pressure sensitive means comprising two springs attached, separately, at one end,,one to each of the furcations of said bracket, andattached'separately, at their other ends, one to each of a pair of adjustable standards adapted to be locked in fixed position relative to said housing after adjustment whereby said springs may be differentially prestressed in any desired manner to provide any desired degree of biasing force on said linkage means.

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